Update C headers to be C++

include/stdarg.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+using va_list = __builtin_va_list;
+#define va_start __builtin_va_start
+#define va_end   __builtin_va_end
+#define next_arg __builtin_next_arg 
+#define va_arg   __builtin_va_arg